Molecular interactions form the basis of healthy metabolism as well as the manifestation of disease, and comprise the very foundation of drug treatment. Tools available to study molecular interactions in their nascent environment and physiological concentrations without chemical modification, such as surface immobilization or labeling, are limited. Current label-free technologies cannot perform homogeneous (free solution) measurements of membrane protein target interactions. Membrane proteins, which make up about 1/3 of the human proteome, interact with a wide range of biologically relevant species. A specific class of membrane proteins known as G-protein coupled receptors (GPCR) is of particular interest, as they represent the principle drug target for about 40% of all prescription pharmaceuticals and over half of the top one hundred best selling drugs. Currently, there does not exist a practical label-free means to study GPCR - lead interactions as they proceed in their native environment. Consequently, label-free approaches significantly under-serve a major drug discovery need, and as such, there exists a profound requirement for a label-free technique to support research demands in the all important GPCR and membrane protein fields. Molecular Sensing Inc.'s (MSI) Phase II SBIR proposal entitled, High Throughput, Label-free Molecular Interaction Platform for Membrane Protein Targets, leverages the achievements of our Phase I program and is directed towards producing a robust Back-Scattering Interferometry (BSI) instrument for use in drug research. In addition to refining the platform, under Phase II we will demonstrate the unique strengths and capabilities of BSI to significantly advance progress in the all important area of membrane protein drug research by capitalizing on collaborations with three world-class research environments: The Groves Laboratory at the University of California at Berkeley, the Finn Laboratory of Scripps Research Institute, and the Bornhop Laboratory at Vanderbilt University. The culmination of our Phase II program will result in the creation of a prototype research product, which the company will sell to its early access customers in translational and pharmaceutical research markets. Phase III activities will complete the product development process, making this powerful new tool accessible to laboratories worldwide. As our initial market experience of Phase I technology has taught, our commercial product will create a sustained impact to basic, translational, and drug discovery research that will positively influence healthcare through the accelerated release and development of new and powerful therapeutics and diagnostics, consistent with the mission of the National Institutes of Health.